Harvesting a new water source – right at home

Mark Weston

With record-breaking rainfall, it’s hard to talk about future water shortages. In fact, they are a reality unless we develop new water. New water supplies will not come by dragging icebergs to San Diego or building pipelines to Canada. The answer is much simpler and closer to home. Our next new water supply will come from purifying wastewater with today’s advanced technologies to produce drinking water. This technology is sound, proven and reliable.

San Diego County water agencies have never lost sight of securing the next reliable water supply to meet the needs of our residential, commercial, industrial and agricultural communities. Today, we import 90 percent of our water. Looking ahead into the 21st century, our water supplies are threatened by drought, environmental rulings, water shortages, climate change, growth and natural disasters.

Water conservation helps greatly. Water agencies have seen a 20 percent to 30 percent drop in demand over the last three years. Conservation will always be important and we will continue to encourage water-efficient landscaping. However, it is time to look further into the future to develop new water supplies.

The same technology that is used to desalinate ocean water is used to create new water from wastewater at a lower cost with enhanced environmental benefits. Highly treated wastewater is commonly used for irrigation throughout the county. Further, treating this water by using microfiltration, 100 percent reverse osmosis and advanced disinfection produces water that meets or exceeds all drinking water standards. Filtering this water through the natural sands in a groundwater basin is the final step.

Using this technology, Orange County Water District produces 70 million gallons of drinking water a day that is injected into the groundwater basin and delivered to thousands of homes and businesses every day. Water agencies globally use these technologies to meet drinking water demand.

Helix Water District and Padre Dam Municipal Water District, located in the East County, are partnering to develop the $200 million El Monte Valley Project. The plan calls for producing highly purified water from wastewater using 100 percent reverse osmosis at Padre Dam’s Water Reclamation Facility in Santee. This purified water will be piped 11 miles to the El Monte Valley, east of Lakeside, where it will be percolated into the groundwater basin. The water will be retained in the aquifer for a minimum of six months where it will blend with naturally occurring groundwater. This groundwater will be removed and mixed with Helix’s raw water supplies and then treated again at the R.M. Levy Water Treatment Plant for delivery to customers, creating 5,000 acre-feet of new water to meet 15 percent of Helix’s needs.

The 580-acre project, on land owned by Helix, will include surface sand mining to re-contour the valley, removal of non-native plants, restoration of the San Diego River channel, creation of hiking/equestrian trails and planting of enhanced wildlife habitat. Securing this new water supply will add about 5 percent to the cost of water. The project costs would be offset in part by sand sales, state and federal grants, and wholesale subsidies.

An environmental impact study will be done this year with all approvals anticipated in 2013. The public will be an active partner in this project. Impacts to the valley will be analyzed and mitigated through the environmental review. Based on the science and technology of the 21st century, this locally controlled, drought-proof source of highly purified water can be our next new water supply, supplementing our limited imported water supplies.